Incorporation of selectivity factor in modeling binary component adsorption isotherms for heavy metals-biomass system

The single and binary biosorption of copper and lead ions from aqueous solution using a low cost agro-based resource (i.e. rice straw) has been demonstrated in this work. The biosorption experiments were performed in a static mode. Experimental parameters affecting the sorption process namely biosorbent dose, pH, and temperature were studied. Two empirical adsorption models (i.e. Langmuir and Freundlich) were used for the evaluation of biosorption equilibrium data in single system. Both models were able to correlate experimental data satisfactorily. The adsorptivity of solute (KL) and maximum sorption capacity of the solid (qm) were increased at higher temperatures. For binary metal system, we modified the adsorption parameters of extended-Langmuir model (i.e. KL-bin and qm-bin) by introducing selectivity factor of the solute (S). It was found that the modified extended-Langmuir model with incorporation of solute’s selectivity factor gave good correlation results against binary adsorption data with reasonable fitted parameter values. The feasibility and biosorption performance of rice straw in sequestering copper and lead ions was also tested using real effluent along with its regeneration possibility.

► Utilisation of rice straw as a cheap and effective sorbent for the removal of Cu and Pb ions.
► Incorporation of selectivity factor of solute for the modification of extended-Langmuir model.
► Representation of binary adsorption data and the model fittings in 3D plots.
► Application of biosorption study using real effluent from a wastewater treatment plant.
► Regeneration study of biosorbent for industrial practice.